Author Topic: Turning Questions (Read 833 times)

Smoothbore · « **on:** October 05, 2005, 09:57:35 AM »

I friend who is rebuilding a rather large (and old) boat was at a prop shop recently, and being the friend that he is, asked them if they had any shafting scrap around. As a result he brought me a 2 1/4" dia. by 13 3/4" long round of Aquamet # 19.

According to their web site it is a modified form of 304 stainless. Being a "duffer" with my small lathe, I have no experience with turning any type of stainless, and thus, seek some help/info/tips/tricks, etc. from any of you forum members who are experienced along this line.

From a lot of previous threads, it is obvious a number of you have machine shops, big lathes---and lots of experience. Any and all help to work with this material will be very much appreciated.

Thanks,
Smoothbore

Cat Whisperer · « **Reply #1 on:** October 05, 2005, 11:49:24 AM »

304 Stainless is right-much tough stuff; whereas 303 is a dream to cut.

Take that with a grain of salt, as it's the same that I heard about 17-4, which I like very much.

As with anything else, start with light cuts and learn it's characteristics and learn how to get the finish you need.

GGaskill · « **Reply #2 on:** October 05, 2005, 11:52:20 AM »

What kind and size lathe do you have?

Cat Whisperer · « **Reply #3 on:** October 05, 2005, 12:52:12 PM »

Quote from: GGaskill

What kind and size lathe do you have?

George -

(I assume the question is directed to smoothbore, but I have two 13x38 with 4hp 3phase motors.)

Smoothbore -
I can send you some scrap pieces of 303 in 1" and 1-1/4" to play with if you like.

GGaskill · « **Reply #4 on:** October 05, 2005, 01:07:18 PM »

Yes, it was directed to Smoothbore, but 4 HP would be nice. My Logan is 1 HP and the big LeBlond is 1.5 HP, but it is a lot stronger than the Logan, much moreso than the 1 vs. 1.5 would imply.

Cat Whisperer · « **Reply #5 on:** October 05, 2005, 01:11:09 PM »

The 4hp has a drawback - these two came from a high school program, so when (and they were) the crashes happened the battle scars were not superficial. :eek:

kappullen · « **Reply #6 on:** October 05, 2005, 04:56:52 PM »

Smoothebore,

That being 304 ss, has a couple of poor machining properties.

Among metals, 304 is one of the most insulating ones around.
Another property is that it will work harden.
It tends to be a bit abrasive as well.

These properties combine to a material that tends to hold the heat at the cutting edge, and wear your tool. When a critical temperature is reached, voila it workhardens and busts your tools.

You need a free cutting tool (positive rake), slow cutting speed, and to keep it cool with ample cutting fluid.

This material is excellent in corrosive applications and makes beautiful finishes when done right.

That is a tough one for a beginner to be deep drilling in.

I would drill a lead hole because the chisel point of a large drill will work harden the bottom of the hole and cause you grief.

Just pray that it's really 303fm.

Good luck!

kap

Cat Whisperer · « **Reply #7 on:** October 06, 2005, 12:25:57 AM »

Now you know the reasons.

Thanks, Kap, for giving the technical details. I'd not researched the differences between 303/304, I just knew of the reputations of 304 and had a bit of experience with 303. Caught your reference to 303fm - I assume Free Machining - that makes sense.

Smoothbore · « **Reply #8 on:** October 06, 2005, 12:43:57 AM »

Thanks for the replies, especially Kappullen. What you and the several others have said has convinced me, at least for the near future, is to leave this piece of material in the box. As (Ggaskill) my lathe is a Jet 7 x 20 (all you folks with real lathes please stop laughing). However for what I originally purchased it for (rocketry) it has served me well, despite my having to learn as I went with it. As far as its' capacity and accuracy goes it has done well for me making small bronze cannons and mortars.

Obviously, bigger or harder stuff to work with have to wait until I somehow gain access to the use of a real lathe.

Again thanks for the replies.

Smoothbore

Cat Whisperer · « **Reply #9 on:** October 06, 2005, 12:55:07 AM »

No laughter here.

One of my personal philosophies of life is to take whatever I've got and squeeze the maximum performance or quality from it. You've got a serviceable machine - make it perform by being the master of it. Look at the quality of work that was done in the 1800's and earlier on machines that are crude in todays standards! Craftsmanship!

GGaskill · « **Reply #10 on:** October 06, 2005, 07:59:35 AM »

My first lathe was/is (I still have it) a Unimat SL with the rod ways. It works OK with free cutting materials like brass and aluminum but is really overmatched by steel.

You just need to keep in mind the limitations of the machine when you choose which materials and techniques to use. A bigger machine allows you to be more aggressive in material removal but the principles remain the same.